SAT-514 The Decrease in Serum Parathyroid Hormone on Vitamin D Treatment Is Similar When Comparing Increases in Serum Free or Total 25 Hydroxyvitamin D in White and Black Women

Background: Recent advances in measurement of total serum 25OHD (T25D) led to development of free 25OHD (F25D) assays. The free hormone hypothesis states that only F25D which is about 0.02% of T25D is available for conversion to the active metabolite 1,25(OH)2D, the rest is bound to D binding protein (DBP) and albumin. In a previous paper (J Int Med 2018 Aug 23 online)we did not find a change in BMD or bone markers compared to F25D or T25D. A...